translation patches (usually .ips files for snes emulation) take the entire body of text (or less than the entire body of text) and replace it with text in the desired language.

as long as you aren't too interested in deviating from the original character limits, it's not too difficult to do, but patching a game to change the functionality, or to make room for longer messages, alter sprites or game mechanics, etc require actual programming knowledge 8D

it's pretty interesting. I never bothered until someone in japan released a patch for SNES FFV called Ancient Cave that basically turns turns the game into a roguelike